1. Field
Embodiments relate to a heterocyclic compound, and an organic light-emitting diode and a flat display device including the heterocyclic compound, and more particularly, to a heterocyclic compound that is suitable for use as a light-emitting material or electron transporting material included in an organic light-emitting diode, an organic light-emitting diode including the heterocyclic compound, and a flat display device including the organic light-emitting diode. The organic light-emitting diode including an organic layer including the heterocyclic compound has a low driving voltage, high luminescence efficiency, and long lifetime.
2. Description of the Related Art
Organic light emitting diodes are self-emission devices that have a wide viewing angle, a high contrast ratio, a short response time, and excellent brightness, driving voltage, and response speed characteristics, thus enabling the generation of multi-color images.
In an organic light-emitting diode, an anode may be formed on a substrate, and a hole transport layer, an emission layer, an electron transport layer, and a cathode may be sequentially formed in this stated order on the anode. In this regard, the hole transport layer, the emission layer, and the electron transport layer may be organic films including organic compounds. When a voltage is applied between the anode and the cathode, holes injected from the anode pass the hole transport layer to the emission layer, and electrons injected from the cathode pass the electron transport layer to the emission layer. The holes and electrons, which are carriers, are recombined in the emission layer to generate excitons, which then change from an excited state to a ground state, thereby generating light.
An emission layer material of an organic light-emitting diode may include anthracene derivatives. An electron transport material may include Alq3, TBPi, PBD, PF-6P, PyPySPyPy, etc. An organic light-emitting diode may use a 2 or 3 equivalent amount of a compound of phenyl anthracene. However, a device using the 2 or 3 equivalent amount of the compound of phenyl anthracene may have two or three anthracenes covalently linked. Thus, an energy gap may be narrow and color purity of blue light emission may be low. Also, the 2 or 3 equivalent amount of the compound of phenyl anthracene may be oxidized and thus, purification thereof may be difficult. Accordingly, organic light-emitting diodes using either an anthracene compound in which naphthalene is substituted at sites 1 and 9 of an anthracene group or a diphenylanthracene compound in which an aryl group is substituted at an m-site of a phenyl group may be used. However, such organic light-emitting diodes may have low luminescence efficiency. Also, an organic light-emitting device may use a monoanthracene derivative substituted with a naphthalene. However, such an organic light-emitting diode may not be practical due to its low luminescence efficiency of about 1 cd/A. Also, an organic light-emitting diode may include a compound having the structure of phenyl anthracene. However, the compound may be substituted with an aryl group at an m-site thereof. Thus, the compound may have a luminescence efficiency as low as about 2 cd/A, although its heat resistance is high.